U.S. patent number 4,589,339 [Application Number 06/649,899] was granted by the patent office on 1986-05-20 for rubber blanket for an offset rotary printing machine.
This patent grant is currently assigned to M.A.N. Roland Druckmaschinen Aktiengesellschaft. Invention is credited to Hermann Fischer.
United States Patent |
4,589,339 |
Fischer |
May 20, 1986 |
Rubber blanket for an offset rotary printing machine
Abstract
To relieve stresses within the rubber of a rubber blanket of a
rotary offset printing machine, and prevent escape or squeeze-out
of the rubber layer as the blanket rotates, the blanket is formed
with interruptions or stress reliefs which, when the blanket is
laid out flat, are located in zones corresponding to zones of the
printed carrier which are free from printed subject matter, for
example along fold lines of the carrier, surrounding pictures or
non-printed subject matter, or the like. The interruptions or
reliefs can be made by milling, for example longitudinal and
transverse notches or grooves (2, 3) or by punching holes through
the rubber layer (14), the holes being aligned in single or
multiple rows along the zones free from printed subject matter.
Stresses within the rubber layer, thus, can be relieved not only at
the lateral edges, but also inwardly, and centrally, thereby
improving overall register of printed subject matter.
Inventors: |
Fischer; Hermann (Augsburg,
DE) |
Assignee: |
M.A.N. Roland Druckmaschinen
Aktiengesellschaft (Offenbach am Main, DE)
|
Family
ID: |
6211047 |
Appl.
No.: |
06/649,899 |
Filed: |
September 12, 1984 |
Foreign Application Priority Data
Current U.S.
Class: |
101/217;
101/376 |
Current CPC
Class: |
B41N
10/02 (20130101); B41N 2210/06 (20130101); B41N
2210/14 (20130101); B41N 2210/02 (20130101) |
Current International
Class: |
B41N
10/00 (20060101); B41N 10/02 (20060101); B41F
005/22 (); B41F 007/02 (); B41F 013/08 () |
Field of
Search: |
;101/217,218,177,137,142,143,154,395,396,375,376 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
129759 |
|
Feb 1978 |
|
DD |
|
2080204 |
|
Feb 1982 |
|
GB |
|
Primary Examiner: Fisher; J. Reed
Attorney, Agent or Firm: Frishauf, Holtz, Goodman &
Woodward
Claims
I claim:
1. For combination with an offset printing machine cylinder of a
rotary offset printing machine,
a blanket structure comprising
a rubber-like cover layer (14,16) of a flexible ink-receiving and
transferring material; and
a textile base (13,15) located beneath the cover layer,
the cover layer and the textile base being bonded together,
for printing on a printing carrier of subject matter which leaves
selected zones of the printing carrier free from printed subject
matter,
comprising, in accordance with the invention,
means for decreasing stresses arising in the cover layer upon
operation of the printing machine including
interruptions (2,3; 5-8; 10, 11, 12) formed in the cover layer
(14,16) and positioned in non-printing zones corresponding to the
zones of the carrier free from printed subject matter.
2. Blanket according to claim 1, wherein the interruptions (2, 3;
5-8) are formed as grooves or notches.
3. Blanket according to claim 1, wherein (FIG. 3) the interruptions
are formed as perforating openings or holes located in at least one
longitudinal row and penetrating through said cover layer (14).
4. Blanket according to claim 1, wherein the interruptions are
located in cutting or folding zones of the carrier.
5. Blanket according to claim 1, wherein the interruptions are
formed as continuous milled grooves.
6. Blanket according to claim 1, wherein the interruptions are
formed as serially arranged punched perforations extending through
the cover layer and located in at least one row positioned parallel
to an edge line of the carrier.
7. Blanket according to claim 1, wherein the interruptions extend
in a directions parallel to the axis of the cylinder.
8. Blanket according to claim 1, wherein the interruptions extend
in a direction circumferentially with respect to the cylinder.
9. Blanket according to claim 1, wherein the interruptions include
at least one portion of interruptions extending parallel to the
axis of the cylinder and at least one further portion of
interruptions extending in a direction circumferentially with
respect to the cylinder.
10. Blanket according to claim 7, wherein the interruptions (2, 3;
5-8) are formed as grooves or notches.
11. Blanket according to claim 7, wherein (FIG. 3) the
interruptions are formed as perforating openings or holes located
in at least one longitudinal row and penetrating through said cover
layer (14).
12. Blanket according to claim 7, wherein the interruptions are
located in cutting or folding zones of the carrier.
13. Blanket according to claim 8, wherein the interruptions (2, 3;
5-8) are formed as grooves or notches.
14. Blanket according to claim 8, wherein (FIG. 3) the
interruptions are formed as perforating openings or holes located
in at least one longitudinal row and penetrating through said cover
layer (14).
15. Blanket according to claim 8, wherein the interruptions are
located in cutting or folding zones of the carrier.
Description
The present invention relates to a blanket, such as a rubber
blanket, for use on the blanket cylinder of a rotary offset
printing machine, and more particularly to a rubber blanket which
is a composite of a textile substrate and a cover layer of rubber
or plastic which transfers ink on the material to be printed,
typically on a paper web or paper sheet.
In the specification that follows, and for simplicity, the
structure will be referred to as a "rubber blanket" although, of
course, materials other than rubber can be used, and the term
"rubber" should be understood here to include any suitable printing
surface which is ink-accepting. Since, usually, such a surface is
rubber, or a rubber-like plastic, the term "rubber" will be used
herein.
BACKGROUND
Rubber blankets, when used in rotary printing machines, are
subjected to stresses which occur as the rubber blanket cylinder
rotates in contact with a plate cylinder. The result of such
stresses is the build-up of a bead extending parallel to the axis
of the cylinder, which, in due course, results in a lateral
squeeze-out or escape of the trailing region of the edge portions
of the rubber blanket. These stresses and strains within the rubber
blanket may lead to partial failure of proper register. This is
particularly noticeable in the region of the printing material
which receives ink in the zones of the rubber blanket which tends
to form the lateral escape or deflection regions.
THE INVENTION
It is an object to improve an ink-accepting, as defined a rubber
blanket cylinder, such that errors and failure of register due to
build-up of stresses within the blanket can be avoided.
Briefly, the rubber blanket is subdivided by interruptions, such as
notches, grooves, or periodic perforations, which are placed in
zones where no ink is to be transferred anywhere, for example in
regions where paper is to be folded, in marginal regions, or the
like.
Forming grooves, discontinuities or perforations in the rubber
coating of the blanket eliminates or at least substantially and
effectively decreases the build-up of stresses, and thus
strain-like deformation of the rubber coating, which is effective
both in circumferential direction of the cylinder as well as in
longitudinal direction. The grooves extend, for example, in the
form of borders around subject matter where no printing is to be
carried out. The decrease in stresses occurs not only once upon
each rotation of the blanket cylinder, but already during printing
within the zones bordered by the interruptions, such as grooves or
other discontinuities of the rubber blanket. The rubber blanket,
thus, can relieve stresses which occur in those regions in which no
ink is to be transferred to the printed material, for example, in
zones which later on are to be folded, where a sheet is to be cut,
in margins, or the like. The moduli of elasticity, that is, the E
moduli of the underlying textile substrate and of the rubber layer,
differ; this difference further contributes to relief of stress on
the rubber blanket layer.
DRAWINGS
FIG. 1 is a plan view of a blanket in accordance with a first
embodiment of the invention;
FIG. 2 is a plan view of a rubber blanket, before being wrapped
about a cylinder, illustrating another embodiment;
FIG. 3 is a fragmentary view of a portion of the blanket for
example of FIG. 1;
FIG. 4 is a cross section through a relief formed in accordance
with FIG. 3; and
FIG. 5 is a cross section through another form of a relief in the
shape of a continuous groove, for example in accordance with FIG.
1.
DETAILED DESCRIPTION
The rubber blanket 1 (FIG. 1) is formed with two reliefs or
interruptions 2, 3 in the form of straight grooves or notches cut
into the rubber blanket. The notch 2 is located in that region in
which no ink is to be transferred to the printed substrate, for
example a web or a sheet of paper, since the substrate is folded
with its first longitudinal fold at the region of the notch 2.
Similarly, a notch 3, extending transversely to the notch 2, is
formed, in which, again, no ink is to be transferred to the
substrate since the first transverse or cross fold will be made at
that region. Due to this arrangement--the crossed interruptions or
reliefs of the rubber layer of the rubber blanket--stresses within
the rubber blanket can be reduced already during printing
therefrom. The notch 3, particularly, reduces the ridge or bead
formed in the direction of the arrow a as the blanket rotates
against the printed subject matter and/or the plate cylinder,
since, already after half a revolution, the rubber blanket can
relieve the stresses arising therein, and the first stress
reduction will occur as the interruption or groove 3 passes a
printing or subject matter transfer line. The groove or notch 2
permits escape and reduction of stresses in the direction of the
arrows c, so that the stresses can be relieved by escape of the
rubber beyond its unstressed dimension also centrally, and not only
at the edge, in accordance with the prior art, that is, along the
arrows b. Any lateral escape or deviation in the direction of the
arrows b is substantially reduced.
The blanket 4 of FIG. 2 is formed with interruptions or reliefs 5,
6, 7, 8, cut in the form of grooves in regions on which no printing
is to be carried out. These grooves 5, 6, 7, 8 border or surround
the subject matter to be printed.
The notches 5-8 may be located, for example, in the region of
margins of pictures or prints. In contrast to the blanket of FIG.
1, which can be pre-cut and made to print any desired subject
matter, the blanket 4 must be specifically arranged and cut for
each printing job, since the reliefs or interruptions 5-8 are
individually matched to the subject matter to be transferred by the
blanket cylinder. The reliefs or interruptions 5-8 again reduce the
build-up of stresses within the rubber blanket by permitting
slightly lateral escape of rubber material of the rubber layer
within central regions or portions of the blanket and not only at
the edges.
The reliefs or interruptions need not be continuous grooves; as
seen in FIG. 3, the blanket 9 is formed with reliefs 10, 11 which
may be constructed as a single-line or track perforation within the
rubber material--see perforating lines 10, 11. Rather than using a
single line, double or triple or even more lines or rows of
perforation openings may be used--see, for example, the central
perforation line 12 which may be placed along the first
longitudinal fold, for example, corresponding to the position of
groove 2 of FIG. 1.
The rubber blanket 9 (FIG. 3) has a textile base or support
substrate, and a cover layer 14 of rubber or plastic, that is, of a
material which accepts the ink and transfers ink to the print
carrier, typically webs or sheets of paper. The reliefs or
interruptions 10 are formed as perforations, that is, holes, which
extend only within the blanket or rubber layer 14. Such holes can
be provided on the blanket layer by punching or stamping, for
example, before bonding the rubber layer to the textile substrate
13.
The reliefs or interruptions 2, see FIG. 1, can be formed also in
form of grooves or notches. FIG. 5 illustrates the textile
substrate carrier 15 with the cover layer 16 forming the rubber
blanket, in which grooves of V-shaped cross section are provided.
The reliefs 2 may, of course, be formed differently, for example
grooves having rectangular or U-shaped cross section are suitable.
The grooves 2 can be made by milling, for example by passing the
blanket under a suitably shaped milling cutter. The maximum width
of a groove 2, or the diameter of a perforation hole 10, is
preferably approximately in the same order as the thickness of the
rubber cover layer 14, 16, respectively.
Various changes and modifications may be made, and features
described in connection with any one of the embodiments may be used
with any of the others, within the scope of the inventive
concept.
* * * * *